JP3095705B2 - Plastic bindings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binding device, and more particularly, to a plastic binding device having a support member which is inserted into a binding hole formed in an object such as a loose leaf.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a spherical engaging portion 1 as shown in FIG. A plastic binding device 7 having a pair of support members 5, typically a pair of support members 3 having a cylindrical support portion 3 below the entrance 1, is used. The spherical engaging portion 1 is dimensioned and shaped so as to be resiliently engageable with a corresponding receiving hole (not shown) provided on the binding device 7 and opposed to the engaging portion 1. The columnar support portion 3 has a solid structure together with the spherical engagement portion 1 so that the columnar support portion 3 does not bend due to the weight of the loose leaf bound.

[0003] However, when such a solid cylinder is molded from a plastic material, the cylinder is generally cooled gradually from the outer portion toward the central portion upon cooling and hardening after being removed from the mold after molding. Upon cooling, vacuum bubbles may be generated along the central portion due to shrinkage strain on the already hardened outer portion. Such vacuum bubbles cause a problem in appearance particularly when the support member is made of transparent plastic. In order to solve this problem, if the support portion is formed in the shape of a pipe 9 as shown in FIG. 4, the strength of the support portion is lower than when the support portion has a solid structure. It breaks without enduring. Further, when the inner diameter of the pipe 9 is reduced, the strength of the mold is extremely reduced.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a binding device having a column member that does not generate a vacuum bubble along a center portion of the column portion.

[0005]

According to the present invention, there is provided a plastic material having a column member 10 molded into a solid cylindrical shape and adapted to be inserted into a binding hole formed in a workpiece such as a loose leaf. A binding device formed by forming a slit 24 having a protruding depth along the longitudinal direction of the support member 10 and reaching the central axis 28 of the support member at the time of molding. Is solved. In one embodiment of the present invention, the slit 24 of the strut member 10 has a wedge-shaped cross-sectional shape, and the strut member 10 can be integrally molded with the binding device or separately molded and then integrated with the binding device. Shall be.

[0006]

FIG. 1 shows a perspective view of a binding device 12 having a support member 10 according to the present invention. Binding device 12
For example, a lower member 14 for fixedly attaching to a binder member (not shown) via a suitable fastener such as a rivet, and a back side integrally connected along one side of the lower member 14. It is composed of a member 16 and an upper member (not shown) integrally connected along one side of the back member 16, and is entirely made of plastic. Prop member 10
Are provided in a pair extending vertically from the upper surface 18 of the lower member 14 toward the upper member, and are integrally formed with the lower member 14 in the illustrated embodiment.

The pillar member 10 has a spherical tip portion, and the spherical tip portion constitutes a spherical engaging portion 20 which can be resiliently disengaged from a receiving hole formed at a corresponding position of the upper member. I do. A portion below the spherical engagement portion 20 is formed as a column-shaped support portion 22, and an object such as a loose leaf is held by the support portion 22. A slit 24 having a constant rush depth is opened in the support portion 22 along a predetermined length in the longitudinal direction. In the illustrated embodiment, the slit 24 has a wedge-shaped cross-sectional shape. In forming the slit, a mold portion 26 having a wedge-shaped cross-sectional shape as illustrated in FIG. When the support member 10 is molded, the slits 24 are simultaneously formed in the support portion 22.

The slit 24 is formed so as to have a penetration depth reaching the central axis 28 of the column portion 22 or at least near the central axis. By forming the slit 24 having such a rush depth, the material heat of the central portion of the support portion 22 is radiated simultaneously with the outer portion when the support member 10 is cooled and hardened. Accordingly, the difference in the contraction speed of the material between the outer portion and the central portion is reduced, and vacuum bubbles along the central portion of the column portion 22, which have been a problem when no slit is provided, are not generated.

While the invention has been described with reference to illustrative embodiments, it will be understood that many modifications may be made within the invention. For example, the spherical engagement portion 20 may have any other shape as long as it can be resiliently disengaged from the corresponding receiving hole of the upper member of the binding device, and the slit 24 is formed by the central axis 28.
Alternatively, it may be formed as a cross-sectional shape other than the wedge shape, as long as it has a depth of penetration into the vicinity thereof.
Alternatively, rather than having the strut member 10 be integrally molded with the binding at the time of molding, it can be molded separately and then retrofitted integrally with the binding using any suitable fastening member. It is also possible.

On the other hand, when the binding thickness of the binder member to be attached is large, and therefore, it is necessary to make the strut member 10 relatively long, if one slit 24 is formed over the entire length of the strut member, some force may be generated. In addition, when the support member 10 is bent, the slit 24 opens laterally at the bent position, and the slit 24 is slightly plastically deformed in the opened state. Therefore, the support member cannot be restored to the original completely upright state by its own elasticity. Accordingly, for a relatively long strut member, the slit 24 is divided in the longitudinal direction to prevent such deformation of the slit as illustrated in FIG. 5, and a strut portion 30 for reinforcement is left between the slits. Can be

[0011]

According to the present invention, there is provided a binding device having a column member which does not generate a vacuum bubble along a center portion of the column portion.

[Brief description of the drawings]

FIG. 1 is a perspective view of a support member according to the present invention.

FIG. 2 is a cross-sectional view of FIG. 1 taken along line aa.

FIG. 3 is a perspective view of a conventional support member.

FIG. 4 is a cross-sectional view of the column portion when the column portion is formed in a pipe shape.

FIG. 5 is a perspective view of a support member according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 support member 12 binding device 14 lower member 16 back member 18 upper surface 20 spherical engaging portion 22 support portion 24 slit 26 mold portion 28 central axis 30 reinforcing portion

Claims (4)

(57) [Claims] 1. A plastic material binding device having a support member (10) molded into a solid cylindrical shape and adapted to be inserted into a binding hole formed in an object to be bound such as a loose leaf, A binding device, wherein a slit (24) having a depth of penetration extending along the longitudinal direction of the support member (10) and reaching the central axis (28) of the support member is formed during the molding. 2. The binding device according to claim 1, wherein the slit (24) of the strut member (10) has a wedge-shaped cross section. 3. The binding device according to claim 1, wherein the strut member (10) is integrated with the binding device after being integrally molded or separately molded. 4. The binding device according to claim 1, wherein a plurality of slits (24) are formed in a longitudinal direction of the support member (10).